Question

Write C++ statement(s) that accomplish the following. a. Declare int variables x and y. Initialize x to 25 and y to 18. b. Declare and initialize an int variable temp to 10 and a char variable ch to 'A'. c. Update the value of an int variable x by adding 5 to it. d. Declare and initialize a double variable payRate to 12.50. e. Copy the value of an int variable firstNum into an int variable tempNum. f. Swap the contents of the int variables x and y. (Declare additional variables, if necessary.) g. Suppose x and y are double variables. Output the contents of x, y, and the expression x + 12 / y - 18. h. Declare a char variable grade and set the value of grade to 'A'. i. Declare int variables to store four integers. j. Copy the value of a double variable z to the nearest integer into an int variable x.

Short answer

Use C++ statements to declare, initialize, and manipulate variables as specified in each task, including swapping values and type conversion.

Step-by-step solution

Declare and Initialize Variables

Declare integer variables `x` and `y`, and then initialize `x` to 25 and `y` to 18 using the following statements: ```cpp int x = 25, y = 18; ```

Declare and Initialize Multiple Variables

Declare an integer variable `temp` initialized to 10 and a character variable `ch` initialized to 'A' with the statements: ```cpp int temp = 10; char ch = 'A'; ```

Update the Value of x

Update the integer variable `x` by adding 5 to its current value: ```cpp x = x + 5; ```

Declare and Initialize Double Variable

Declare and initialize a double variable `payRate` to 12.50: ```cpp double payRate = 12.50; ```

Copy Integer Value

Copy the value of an integer variable `firstNum` into another integer variable `tempNum` assuming `firstNum` has been declared and initialized earlier: ```cpp tempNum = firstNum; ```

Swap x and y Values

Swap the contents of `x` and `y` using an additional temporary variable: ```cpp int tempSwap = x; x = y; y = tempSwap; ```

Output Double Variables and Expression

Assuming `x` and `y` are double: ```cpp double x = 25.0, y = 18.0; cout << "x: " << x << ", y: " << y << ", Expression: " << x + 12 / y - 18 << endl; ```

Declare Char Variable

Declare a character variable `grade` and set it to 'A': ```cpp char grade = 'A'; ```

Declare Variables for Four Integers

Declare integer variables to store four integers: ```cpp int num1, num2, num3, num4; ```

Convert Double to Nearest Integer

Assuming `z` is a double variable, copy its value to the nearest integer to an integer variable `x`: ```cpp x = static_cast(round(z)); ```

Key concepts

Variable Declaration

In C++ programming, declaring a variable means to inform the compiler about the variable’s type and name. This is essential because when you declare a variable, you are allocating space in the computer's memory.
To declare a variable, you need to specify:

• The data type (such as `int`, `char`, `double`, etc.)
• The variable's name (identifier)

For instance, if you declare an integer variable `int x = 25;`, you are telling the compiler that `x` is a variable of type integer and its initial value is 25. Declaring a variable without initializing it will just reserve memory space without assigning a definite value. Always remember that choosing meaningful names for your variables is a good practice to improve code readability.

Data Types

Data types specify the kind of data a variable can hold in C++ programming. They are crucial as they define the operations possible on the data and the way the data is stored.
Common data types include:

• Integer (`int`): Stores whole numbers with no decimal point, like `25` or `10`.
• Character (`char`): Stores single characters enclosed in single quotes, like `'A'` or `'B'`.
• Double: Used for floating-point numbers or numbers with a fraction, such as `12.50` or `0.0034`.

You would choose the appropriate data type based on the needs of your program to ensure data accuracy and efficient memory use.

Arithmetic Operations

Arithmetic operations in C++ allow you to perform mathematical computations. Understanding how to use these operators is vital for manipulating variables and data in your programs.
The basic arithmetic operators include:

• Addition (`+`): Adds two numbers. For example, `x + 5` increases the value of `x` by 5.
• Subtraction (`-`): Deducts one number from another, like `x - y`.
• Multiplication (`*`): Multiplies numbers. `x * y` multiplies `x` by `y`.
• Division (`/`): Divides one number by another. Keep in mind integer division truncates decimals.
• Modulus (`%`): Finds the remainder when one number is divided by another.

Using these operations, you can modify the value of variables or even resolve complex expressions.

Type Conversion

Type conversion is the process of converting a variable from one data type to another. This can be done automatically or explicitly.
There are two types of type conversion in C++:

• Implicit Conversion: Happens automatically when data types are compatible. For example, mixing `int` and `double` in expressions might lead to implicit conversion to `double` for accuracy.
• Explicit Conversion (Casting): Uses specific syntax to convert data types, often because implicit conversion isn’t happening naturally. This is done using casting operators like `static_cast(value)`, which might convert a `double` like `12.7` to an `int` by rounding it off to `13` using a function like `round()`.

Choosing the right type conversion method ensures your program maintains data precision and integrity.